Dwight Watt Newspaper Article #309
A firewall is a method in networks to block unwanted traffic from getting on a network. It is similar to firewalls in building. Firewalls in buildings block fires from spreading thru a building. They do not allow any openings between sections of the building. Computer firewalls allow some openings but want to allow as few as possible.
Computer firewalls can be hardware or software based.
Hardware firewalls are firewalls that come as separate computers and are attached where traffic first comes in your network
Software firewalls are programs that you run on your computer to block traffic to it. They are the most common and a number of companies sell them and windows includes a firewall program
Firewalls do their work by looking at all the packets that come across the network and either block or block those packets based on the protocols that sent the packets (protocols are sets of rules used to communicate on the network, ones you may have hear of include IP, FTP, HTTP, SMTP and others). These different protocols use different ports to send information across the network and the firewall blocks on the ports. You could set a firewall to only allow HTTP and port 80 and you could look at all the non-secured web sites but nothing else.
The object is just to allow traffic in you want (sorta like letting people have keys to your house, you let some, but not most people and you lock your door) Hackers will look for unused open ports or protocols and use that as a unlocked back door to get in a network and do damage.